I feel your pain. This is the last piece of the puzzle for us.
If you're using a SAN, you might be able to offload the HA to that layer. NetApp filers can be configured to present NFS4 shares, and to have a second point of presence in another datacentre. I think this isn't true HA, though, rather the NetApp will take snapshots from time to time, so there is still the risk of data loss.